The MN blood group of humans is determined by a single locus with two co-dominan
ID: 181211 • Letter: T
Question
The MN blood group of humans is determined by a single locus with two co-dominant alleies, L^M and L^N your are given the opportunity to analyze the blood type data for 1000 Inhabitants of an isolated island population in the Indian Ocean. The inhabitants are a mix of the descendants of natives present before modern travel and of recent European colonizers drawn to the island's tropical climate, beauty and isolation. Use the numbers of individuals of each blood type to calculate the frequencies of the two alleles of this locus: 99M-type(L^M L^M) 252 MN-type (L^M L^N) 649 N-type (L^M L^N) Using the estimations above for the allele frequencies at this locus, predict the proportions and expected numbers of individuals of each blood type in a sample of 1000 individuals according to the Hardy-Weinberg model. Show your calculations. Interpret these findings, indicating 1) whether the observed frequencies of genotypes at the blood type locus fit the expectations of the Hardy-Weinberg model, and 2) what biological processes may explain any observed deviation from the Hardy-Weinberg model. [chi^2 = sigma (O-E)^2/E; 3.84 is the critical value of chi^2 statistic with p=0.05 and 1 d.f.]Explanation / Answer
1. Total number of indiviuals= 1000
MM= 99
MN= 252
NN= 649
1. Calculate Genotypic frequencies:
MM (p2)= 99/1000= 0.99
MN (2pq)= 252/1000= 0.252
NN (q2)= 649/1000= 0.649
Allele Frequency:
According to Hardy-Weinberg equation:
p2 + 2pq + q2 = 1
The population that we have ana;ysed have two alleles at the blood type locus, nd each indiviual will have a combination of these two allels. Thus, this entire population consists of 2000 (1000 X2)alleles at the blood type locus. To determine the allelic frequency we simpe count the number of M or N allele and divide by the total number of alleles. So, the allelic frequency for teh M allele will be:
f(M)= {(2 X 99) + 252}/ 2000= 0.225
f(N)= {(2 X 649) + 252} / 2000= 0.775 (Also, you can calculate it by using p + q=1. where p= 0.225)
According to Hrdy- weinberg law, p + q =1, So
0.225 + 0.775=1. hence, it obeys Hardy-Weinberg model.
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